OPTIMIZATION OF SUBMERGED FERMENTATION CONDITIONS FOR TWO XYLANASE PRODUCERS COPRINELLUS DISSEMINATUS MLK-01NTCC-1180 AND MLK-07NTCC-1181 AND THEIR BIOCHEMICAL CHARACTERIZATION

摘要

Out of 15 isolates, two white-rot basidiomycetes, namely MLK-01 and MLK-07, showed good growth in the pH range of 5.0 to 10.0. Both isolates produced maximal fungal growth and xylanase activity with minimal cellulase contamination at incubation periods of 8 and 9 days, respectively, and pH 10.0 with wheat bran as substrate under submerged fermentation conditions. The maximum xylanase, CMCase and lignin peroxidase activities of isolate MLK-01 were 30.32, 0.32 and 0.25 IU/mL, respectively, with protein concentration of 1.76 mg/mL at pH 7.5 and temperature of 75 degrees C, while those of isolate MLK-07 were 36.37, 0.25 and 0.15 IU/mL with protein concentration of 1.69 at pH 8.0 and temperature of 65 degrees C. Hg2+ and Cu2+ inhibited the xylanase activity for isolate MLK-01 to 17.6 and 20.20%, and for MLK-07 to 82.2 and 70.5%, respectively. All the metallic ions like Ca2+, Mn2+, Fe2+, Pb2+, Mg2+, Ni2+, K+, Na+ and Zn2+ improved the enzyme activity, but the enzyme activity doubled with Zn2+ for isolate MLK-01 and with Fe2+ for isolate MLK-07.